INTERNAL SHIFTER HUB FOR BICYCLE

Abstract

AN INTERNAL HUB TRANSMISSION FOR A BICYCLE The object of this invention is to prevent damage to the movement mechanism in a bicycle and to keep objects from hitting or snagging on the movement mechanism. The bicycle internal shifter hub 10 described herein comprises a hub axle 2], a driver 22, a tubular hub shell 23, a planet gear mechanism 24, an operation mechanism 25, and a bell crank 26, The driver is rotatably supported by the hub axle,and is linked to a hub cog 32. The hub shell has a housing space 23a in its interior, is able to rotate around the hub axle, and is linked to the rear wheel 7. The planet gear mechanism 24 has a plurality of power transmission paths, and transmits power from the driver to the hub shell via one path selected from among the plurality of power transmission paths. The operation mechanism selects one of the plurality of power transmission paths by moving in the hub axle direction. The bell crank can be mounted to the inside of the axial end of the hub axle when mounted to the frame, and moves the operation mechanism in the axial direction.

Full Text

The present invention relates to an internal hub transmission for a bicycle, and more particularly to a bicycle internal shifter hub that can be mounted to the frame of the bicycle, and that transmits the power from an input member to an output member at a specific selected gear ratio.
The present invention relates to an internal hub transmission for a bicycle comprising: a hub axle having an axle axis for retaining the transmission to a bicycle frame; a river rotatably supported relative to the hub axle; an output member rotatably supported relative to the hub axle; a planet gear mechanism having: a sun gear disposed around the hub axle; a gear frame rotatably supported relative to the hub axle; a planet gear rotatably supported on the gear frame and meshing with the sun gear; a ring gear rotatably supported relative to the hub axle and meshing with the planet gear; a first one-way clutch disposed in a transmission path between the driver and the output member; a second one-way clutch disposed in a transmission path between the driver and the ring gear; a clutch member supported on the axle for selectively changing the transmission path between the driver and the output member, wherein the clutch member rotates around the axle in response to rotation of the driver and moves axially relative to the hub axle; and a clutch control component that provides movement of the clutch member in the direction of the axle axis and which engages the clutch member for converting rotational motion of the clutch member into motion of the clutch member in the direction of the axle axis.

Prior Art
Bicycles, particularly recreational bicycles referred to as city cruisers, are
inexpensive and are easy to ride, and are thus widely used to commute to work or school
or for shopping. With this type of recreational bicycle, an internal shifter hub is sometimes
mounted at the rear wheel in order to ride at high speeds over flat terrain or to ride uphill
with minimal exertion.
H0t)m] An internal shifter hub generally comprises a hub axle that is fixed to the
-r
bicycle frame; a hub shell; a planet gear mechanism; an operation mechanism; and a movement mechanism. The hub shell is able to rotate around the hub axle, and has spoke holes around its outer periphery. The driver is rotatably supported on the hub axle, and linked to the hub cog. The planet gear mechanism is disposed in the housing space of the hub shell, and has a sun gear formed on the hub axle, a plurality of planet gears that mesh with the sun gear, a ring gear that meshes with the planet gears, and a gear frame that rotatably links the planet gears and is able to rotate around the hub axle. In the case of a three-speed bicycle, this planet gear mechanism has three power transmission paths: a direct drive position that does not go through the planet gear mechanism, an upshift path in which the ring [gear] is rotated via the planet gears of the planet gear mechanism, and a downshift path in which the planet gears are rotated via the ring gear of the planet gear mechanism. The operation mechanism has an operation rod disposed inside the hub axle such that it can move in the axial direction, and a clutch member that moves in conjunction with the operation rod; this member is used for selecting through its movement one of the plurality of power transmission paths of the planet- gear mechanism.
[*BMBJ There are two types of movement mechanism for moving the operation
mechanism in the axial direction: a bell crank type and direct-pull type that features a chain or cable. A bell crank type has a support member that is mounted at the end of the hub axle, and a swing link that is swingably supported by the support member. One end of the swing link is stopped at a shift cable that is linked at its distal end to a shift lever. The other end of the swing link is struck by an operation rod protruding from the end of the hub axle, and a shift is performed by pushing the operation rod with the swing link. A direct-pull type has a chain or cable linked to the distal end of the operation rod. With a direct-pull type, the chain or cable protrudes from the hub axle end and then curves around and is linked to the shift cable, and a shift is performed by pulling the operation rod.

&886^ With an internal shifter hub such as this, when the shift lever is operated
and the shift cable pulled or played out, the operation rod is moved and the power transmission path is switched by the clutch member.
Problems Which the Invention is Intended to Solve
A direct-pull type has a simpler construction than a bell crank type, and therefore contributes to lower cost. However, a direct-pull type involves directly pulling the operation rod with a chain or cable, so the operating efficiency is lower than with a bell crank type, in which the operation rod is moved by the swinging of a swing link. "Operating efficiency" here refers to the ratio of the operating force actually used versus the operating force inputted. Also, since a direct-pull type involves linking the operation rod to a chain or cable inside the hub axle, the assembly work, operation rod replacement work, and so on are more difficult than with a swing type. Accordingly, a bell crank type of movement mechanism is used more often for internal shifter hubs, and particularly for three-speed internal shifter hubs.
£Mtm» Moreover, regardless of which type of movement mechanism is used,
since the movement mechanism protrudes from the hub axle end, the movement mechanism is susceptible to damage if the bicycle falls over. Such damage to the movement mechanism can in some cases preclude shifting. There is also the danger that the protruding movement mechanism will hit or snag on objects while the bicycle is being ridden.
An object of the present invention is to prevent damage to the movement mechanism and keep objects from hitting or snagging on the movement mechanism in an internal shifter hub.
Means Used to Solve the Above-Mentioned Problems
The bicycle internal shifter hub pertaining to the first invention is a hub which can be mounted to the frame of the bicycle, and with which the power from an input member is transmitted to an output member at the selected specific gear ratio, and comprises a hub axle, a driver, a tubular follower, a power transmission mechanism, an operation mechanism, and a movement mechanism. The hub axle can be fixed to the frame. The driver can be rotated around the hub axle and can be linked to the input member. The follower has a housing space in its interior, can be rotated around the hub axle, and can be linked to the output member. The power transmission mechanism

is disposed inside the housing space of the follower, has a plurality of power transmission paths, and transmits power from the driver to the follower via one path selected from among the plurality of power transmission paths. The operation mechanism is disposed inside the hub axle, such that it can move in the axial direction, and is used for selecting through its movement one of the plurality of power transmission paths. The movement mechanism can be mounted on the hub axle and to the inside of the axial end of the hub axle in a state in which it is mounted on the frame, and is a mechanism used for moving the operation mechanism in the axial direction.
p^WBp With this internal shifter hub, if the movement mechanism is operated remotely via a shift cable, for example, the operation mechanism moves in the axial direction, one of the power transmission paths is selected, and the power is transmitted from the input member to the output member via the driver and through the follower. Because this movement mechanism is mounted to the inside of the hub axle end, it does not protrude beyond the hub axle end, which prevents the movement mechanism from being damaged and makes it less likely that objects will hit or snag on the movement mechanism.
^fltt^" The bicycle internal shifter hub pertaining to the second invention is the hub defined in the first invention, further comprising an energizing member that energizes the outer periphery one way in the axial direction, wherein the movement mechanism moves the outer periphery the other way in the axial direction. In this case, the movement mechanism merely has to push the operation mechanism in one direction, so the structure of the operation mechanism is simpler.
The bicycle internal shifter hub pertaining to the third invention is the hub defined in the first or second invention, wherein the movement mechanism pushes and moves the operation mechanism by swinging. In this case, swinging allows the operation mechanism to be pushed in a narrower space. Furthermore, utilization of this principle allows the operation mechanism to be pushed with less force. \0H& The bicycle internal shifter hub pertaining to the fourth invention is the hub defined in the third invention, wherein the movement mechanism has a support member mounted to the inside of the axial end of the hub axle, and a link member that is swingably supported at its middle by the support member, whose base end can be stopped at a shift operation cable, and whose distal end can strike the operation mechanism. In this case, because the link member swings to the inside of the axial end, the swinging link member also does not protrude from the hub axle end when the

support member is mounted on the hub axle and the shift cable is stopped at the link
member.
|MW] The bicycle internal shifter hub pertaining to the fifth invention is the
-hub defined in the fourth invention, wherein the support member can be mounted to the hub axle to the inside of the frame. In this case, since the support member is mounted further to the inside of the axial end, the support member and link member are protected by the frame, so damage to the movement mechanism is prevented more surely.
The bicycle internal shifter hub pertaining to the sixth invention is the hub
defined in the fourth or fifth invention, wherein the shift operation cable has an inner
cable and an outer cable, the inner cable can be stopped at the link member, and the
outer cable can be stopped at the support member. In this case, moving the inner cable
with respect to the outer casing causes the link member to swing and moves the
operation mechanism in the axial direction.
f€0M# The bicycle internal shifter hub pertaining to the seventh invention is the
' hub defined in any of the fourth to sixth inventions, wherein a groove for exposing the
end of the operation mechanism is formed in the hub axle, and the distal end of the link
member strikes the operation mechanism inside the groove. In this case, forming a
groove in the hub axle allows the link member to strike the operation mechanism
surely, even when the support member is mounted to the inside of the hub axle end.
[ 0014 ] The bicycle internal shifter hub pertaining to the eighth invention is the
hub defined in any of the first to seventh inventions, wherein the operation mechanism has a rod-like member disposed inside the hub axle, and a clutch member that switches the power transmission path by moving in conjunction with the rod-like member. In this case, the striking of the rod-like member by the movement mechanism moves the clutch member in the axial direction, and reliably switches and shifts the power.
Embodiments of the Invention
Overall Structure
In Figure 1, the bicycle in which an embodiment of the present invention has been employed is a recreational bicycle, which comprises a frame 1 having a double-loop type of frame body 2 and a front fork 3, a handle component 4, a drive component 5, a front wheel 6, a rear wheel 7 to which a three-speed internal shift

hub 10 has been mounted, a front braking apparatus 8, and a gear shifter component 9 for operating the internal shift hub 10 close at hand.
J4BMU Various components including a saddle 11, the handle component 4, the
front wheel 6, and the rear wheel 7 are attached to the frame 1.
The handle component 4 has a handle stem 14 fixed to the upper portion of the front fork 3, and a handlebar 15 fixed to this handle stem 14. A brake lever 16, which constitutes part of the front brake apparatus 8, a grip 17, and the gear shifter component 9 are mounted at the right end of the handlebar 15. The gear shifter component 9 is mounted on the brake lever 16 on the inside of the brake lever 16, and is linked with an internal shifter hub 10 by means of a shift control cable 73 comprising an inner cable and an outer cable. The gear shifter component 9 has an ordinary structure having a winding lever for winding the inner cable, and a release lever that releases the winding operation of the winding lever and plays out the inner cable, and as such will nptbe described in detail herein.
£»§A4£4 The drive component 5 has a gear crank 18 that is provided to the lower
portion (bottom bracket portion) of the frame body 2, a chain 19 that goes around the gear crank 18, and the internal shifter hub 10.
Structure of the Internal Shifter Hub
The internal shifter hub 10 is a coaster brake-equipped hub with a three-stage structure including power transmission paths for downshifting, direct drive, and upshifting. As shown in Figure 2, this internal shifter hub 10 has a hub axle 21 fixed to the rear pawl 2a of the frame body 2 of the bicycle, a driver 22 disposed around the outer periphery at one end of the hub axle 21, a hub shell 23 disposed further around the outer periphery of the hub axle 21 and the driver 22, a planet gear mechanism 24, an operation mechanism 25 for selecting a power transmission path, a bell crank 26 for actuating the operation mechanism 25, and a coaster brake 27.
£(BP^ As shown in Figures 2 and 3, the hub axle 21 is a rod-like member which has a larger diameter in its middle and a smaller diameter at both ends, and on which threads are formed at both ends. An operation hole 21a is formed in the axial portion of the hub axle 21 from the right end to the center in Figure 2. A first through-groove 21b that goes through the axis over its entire length is formed in the right end portion [of the hub axle 21] to the inside of a rear pawl 2a when mounted on the frame body 2. A pair of chamfered components 21c (see Figure 6) used for the mounting of the bell crank 26 are formed across from each other around the outer periphery of the portion where the first through-groove 21b is formed. A second through-groove 2ld

that goes through the axis is formed in the vicinity of the bottom of the operation hole 21a. The second through-groove 21d goes through the axis of the hub axle 21 and is inclined by a specific groove inclination angle 3 (see Figure 5) with respect to the axis, and is formed in a twist to the side opposite the forward direction going from the right to the left in Figure 5. This second through-groove 21d is formed by using an end drill of a specific diameter to form holes that go through the axis, and then feeding [the drill] toward the center in the axial direction while the hub axle 21 is slowly rotated in the forward direction. Therefore, this second through-groove 21d is shaped as a continuous spiral in which the through-holes intersecting at both ends rotate gradually according to movement in the axial direction. This groove inclination angle (3 should range from 10 to 50 degrees.
flMI^] One end of the driver 22 is rotatably supported on the hub axle 21 via
balls 30 and a hub cone 31, and a hub cog 32 is fixed around the outer periphery at one end. A plurality of serration inner teeth 22a are formed in the axial direction around the inner periphery at the other end of the driver 22.
The hub shell 23 is a tubular member, and a housing space 23a around the inner periphery thereof houses the driver 22 and the planet gear mechanism 24. The hub shell 23 is able to rotate around the hub axle 21 via balls 33 and 34 and a hub cone 35. Hubs 36 and 37 for supporting spokes 7a (see Figure 1) are fixed at both ends of the outer periphery of the hub shell 23.
Structure of the Planet Gear Mechanism
The planet gear mechanism 24 has a sun gear 40 formed coaxially and integrally with the hub axle 21, a gear frame 41 disposed around the outer periphery of the hub axle 21, three planet gears 42 (only one planet gear is shown in the figure) that mesh with the sun gear 40, and a ring gear 43.
tMMt The gear frame 41 is a tubular member, and is rotatably supported on
the hub axle 21. Three notches 41a are formed in the circumferential direction in the gear frame 41, and the planet gears 42 are rotatably supported by pins 44 in these various notches 41a. Serration inner teeth 41b are formed around the inner periphery at one end of the gear frame 41, and serration outer teeth 41c (Figure 1) are formed around the outer periphery at the other end.
PPS1P] The ring gear 43 is formed in a nearly cylindrical shape, and extends
from the planet gears 42 to the outer periphery of the driver 22. Inner teeth 43b are formed around the inner periphery at the other end of the ring gear 43. The planet
j

gears 42 mesh with the sun gear 40 as mentioned above, but at the same time also mesh with the inner teeth 43b of the ring gear 43.
A notch 43a is formed at one end of the ring gear 43, and a clutch pawl 53 that
makes up part of a first one-way clutch 50 as shown in Figure 4 is swingably supported
by a pin 54 in this notch 43a. This clutch pawl 53 is energized in the standing
direction by a torsion coil spring 55. The first one-way clutch 50 transmits only
rotational drive force in the forward direction from the ring gear 24 [sic] to the hub
shell 23. The clutch pawl 53 meshes with the ratchet teeth 23b formed on the inner
peripheral surface of the hub shell 23 only when the ring gear 24 [sic] has rotated in the
forward direction. Even when in a transmission-enabled state in which the ring gear 24
[sic] rotates in the forward direction, this first one-way clutch 50 is able to switch
between a power transmission state in which the clutch pawl 53 meshes with the ratchet
teeth 23b, and a transmission cutoff state of retraction from the ratchet teeth 23b,
which is accomplished by the movement of the clutch member as discussed below.
[«mm» A second one-way clutch 51 that transmits rotational drive force only in
the forward direction from the driver 22 to the ring gear 24 [sic] is arranged between the driver 22 and the ring gear 24 [sic]. A third one-way clutch 52 that transmits rotational drive force only in the forward direction from the gear frame 41 to the hub shell 23 is arranged between the gear frame 41 and the hub shell 23. The third one-way clutch 52 has a tubular clutch case 56 in which serration inner teeth 56a are formed around the inner periphery at one end. These serration inner teeth 56a engage with the serration outer teeth 41c of the gear frame 41, and the clutch case 56 rotates integrally with the gear frame 41. These two one-way clutches 51 and 52 are unable to perform switching in a transmission-enabled state, unlike the first one-way clutch 50.
Structure of the Operation Mechanism
The operation mechanism 25 is used to select the power transmission path, and has a clutch member 45 and a clutch control component 46.
The clutch member 45 switches the driver 22 and gear frame 41 between a linked state and a separated state, and also switches the first one-way clutch 50 between a power transmittable state and a power cutoff state. The clutch member 45 is positioned around the outer periphery of the hub axle 21 such that it can move and rotate in the axial direction. The clutch member 45 is a tubular member as shown in Figure 4, and has serration outer teeth 45a formed around the outer periphery at one end thereof. The serration outer teeth 45a are slidably engaged with the serration inner teeth 22a. A

large diameter component 45b is formed at the other end of the clutch member 45, and
serration outer teeth 45c are formed around the outer periphery thereof. The serration
outer teeth 45c are able to engage with the serration inner teeth 41b formed on the gear
frame 41. A taper surface 45d is formed between the large diameter component 45b
and one end. This taper surface 45d is provided in order to lower the clutch pawl 53 of
the first one-way clutch 50 from its erected position (power transmission position)
indicated by the solid line to its retracted position (power cutoff position) indicated by
the two-dot chain line. When the clutch member 45 moves from the left to the
downshift position on the right end, the clutch pawl 53 follows along the taper
surface 45d, rides up onto the large diameter component 45b, and is lowered into a
retracted attitude. As shown in Figure 3, two step components 45e and 45f are formed
around the inner periphery of the clutch member 45 with spaces between them in the
axial direction. As shown in Figure 4, a plurality of cam surfaces 47 are formed on the
left step component 45f with spaces between them in the circumferential direction. As
shown in Figure 5, the cam surfaces 47 have a flat surface 47a that is depressed at one
end, a curved surface 47b that leads downstream in the forward direction A of the flat
surface 47a, and an inclined surface 47c that leads upstream. The inclination angle a
with respect to the axis of this inclined surface 47c should be greater than the groove
inclination angle p of the second through-groove 21d, and between 20 and 70 degrees.
^Wi^ The clutch control component 46 moves the clutch member 45 in the
axial direction of the hub axle 21, and engages with the clutch member 45 to convert the rotational drive force of the clutch member 45 into displacement in the axial direction. The clutch control component 46 has a push rod 48 that moves in the axial direction through the operation hole 21a, and a shift key 49 that is pressed to the gear frame 41 side by the push rod 48, as shown in Figure 3.
[
end surface of the actuator 66 and the end component of the strike component 69, and energizes the actuator 66 and the operator 65 away from each other, so that when the actuator 66 presses on the shift key 49, the clutch member 45 is energized to the gear frame 41 side.
JflP] As shown in Figure 4, the shift key 49 is a rod-like member with a
triangular cross section, and when pressed, moves through the second through-
groove 21d while turning in the circumferential direction, that is, while twisting. The
outward movement of the shift key 49 is restricted to within the clutch member 45 by a
stop ring 63 mounted around the inner periphery at the other end of the clutch
member 45. Therefore, [the shift key 49] cannot actually come out of the clutch
member 45 as shown in Figure 4. As a result, the shift key 49 is pressed by the push
rod 48 and moves the clutch member 45 to the left in Figure 3.
£4|W4 The shift key 49 is able to strike the cam surfaces 47 inside the clutch
member 45. If the clutch member 45 is rotated in the forward direction in a state in
which the shift key 49 has struck the flat component 47a of the cam surface 47, then
the shift key 49 is pressed to the guide surface 21c side of the second through-
groove 21d by the inclined surface 47c of the cam surface 47, and its motion to the left
in the axial direction is restricted, so the clutch member 45 moves to the right in the
axial direction. Specifically, the rotational drive force of the clutch member 45 is
converted into displacement in the axial direction to assist shift control.
MfSfek A notch 49a is formed at both ends of the shift key 49, and in this
notch 49a is stopped a second coil spring 61 that is stopped at one end on the hub axle 21. The shift key 49 is constantly energized to the clutch member 45 side by this second coil spring 61. A third coil spring 62 is interposed between the shift key 49 and the clutch member 45. The third coil spring 62 is restricted to a specific overall length, and when compressed, energizes the shift key 49 and the clutch member 45 away from each other before the former strikes the latter. As a result, the clutch member 45 remains at a constant distance from the shift key 49 during movement, and is accurately positioned.
0HM4 Here, the energizing forces of the first through third coil springs 60, 61,
and 62 decrease in that order. Specifically, the spring forces decrease in that order. Here, if the spring force of the first coil spring 60 is less than that of the second coil spring 61, then even if the shift key 49 is pressed by the push rod 48, the first coil spring 60 will bend and the shift key 49 will not move. If the spring force of the second coil spring 61 is less than that of the third coil spring 62, then even if the shift

key 49 is pressed by the second coil spring 61, the shift key 49 will not go into the cam surface 47, and shift control cannot be assisted.
[
. the operator 65 and the actuator 66 inside the operation hole 21a, so it is possible to increase the number of coils and thereby lower the spring force and the spring constant. Accordingly, the spring forces and spring constants of the second and third coil springs 61 and 62 can be further lowered, allowing a reduction in the force required to press the push rod 48 during a shift, that is, the operating force of the winding lever in the shift control component 9. As a result, there is less tension on the inner cable, and the inner cable does not break as frequently.
Structure of the Beli Crank
The bell crank 26 is mounted to the inside of the rear pawl 2a in a state in which
the hub axle 21 is mounted on the frame body 2, as shown in Figures 3, 7, and 8. The
bell crank 26 comprises a support bracket 70 mounted at the chamfered
components 21c, and a link member 71 swingably supported by the support bracket 70.
[ 8889*] The support bracket 70 has a mounting component 70a that sandwiches
the chamfered components 21c, a support component 70b that rotatably supports the
link member 71 in the middle, and a stop component 70c that stops the outer
casing 73a of the shift control cable 73 at the distal end, The support bracket 70 is
mounted on the hub axle 21 such that it cannot rotate and cannot move in the axial
direction, by sandwiching the hub axle 21 with the mounting component 70a and a
mounting band 72 stopped at one end to the mounting component 70a. A link shaft 74
for swinging the link member 71 is mounted on the support component 70b. An outer
stop nut 76 that stops the outer casing 73a is threaded onto the stop component 70c, and
this nut 76 allows the swing attitude of the link member 71 to be adjusted.
[6§i4] The link member 71 is a sheet-form member that has been folded into a
cross sectional groove shape, and has a bottom component 71a, an action arm 71b that extends from one end of the bottom component 71a to the hub axle 21 side, and an inner cable stop arm 71c that extends from the other end of the bottom component 71a to the inside of the hub axle 21 in the direction perpendicular to the action arm 71b. A link shaft 74 is disposed along this bottom component 71a, and the link shaft 74 is mounted to the support component 70b of the support bracket 70 through the base ends of the action arm 71b and the inner cable stop arm 71c. A circular strike component 71d is formed at the distal end of the action arm 71b, and the strike component 71d strikes the rear end of the push rod 48. A cable hanger 75 is rotatably

mounted to the distal end of the stop arm 71c. The inner cable 73b of the shift control cable 73 is stopped at this cable hanger 75, and when the inner cable 73b is pulled by the shift control component 9, the link member 71 swings and a shift is performed.
-"•"Structure of the Coaster Brake
The coaster brake 27 is mounted to the brake case 56.' The coaster brake 27
comprises a brake roller 57 supported by the brake case 56, a cam surface 41d formed
around the outer periphery at the other end of the gear frame 41, and a brake shoe 58
that exerts a braking action on the inner surface at the other end of the hub shell 23.
The brake roller 57 is designed such that it is pushed outward in the radial direction by
the cam surface 4 Id when the driver 22 rotates in the reverse direction. As a result, the
brake shoe 58 comes into contact with and brakes the inner surface of the hub shell 23.
[ 0G9#^ Brake lock tends to occur when the coaster brake 27 is installed. Brake
lock is a phenomenon whereby, if the first one-way clutch 50 is in a power transmission state when the rider pedals backward to brake, the drive force will be transmitted in a state in which the brake is applied, and the brake cannot be released. A pawl cage 59 is mounted to the first one-way clutch 50 in this embodiment in order to prevent this phenomenon.
[£093 ] The pawl cage 59 provides a specific angle of play between the ratchet
teeth 23b of the hub shell 23 and the clutch pawl 53 of the first one-way clutch 50, and allows the brake to be released while the ring gear 43 rotates by this amount of play. Specifically, the pawl cage 59 either prevents the clutch pawl 53 from being erected at a specific angle, or, even if it is erected, allows it to be erected at a position where it cannot stop the ratchet teeth 23b at the specific angle, and delays the time when the clutch pawl 53 is stopped by the ratchet teeth 23b during initial drive.
[mm]
Shift Actuation
Because of this planet gear mechanism 24 and one-way clutches 50 to 52, this internal shifter hub 10 has;
a downshift power transmission path made up of the driver 22, the ring gear 43, the planet gear mechanism 24, the gear frame 41, and the hub shell 23;
1 Translator's note: "56" is referred to as a "clutch case" above; possible error.

a direct drive power transmission path made up of the driver 22, the ring gear 43, and the hub shell 23, and
an upshift power transmission path made up of the driver 22, the clutch member 45, the gear frame 41, the planet gear mechanism 24," the ring gear 43, and the hub shell 23.
££fiiftj Shifting is performed by operating the push rod 48 with the bell crank 26
via the shift control cable 73.
Down shift-Upshift Actuation
In the state shown in Figure 3, in which the push rod 48 is not pushed in, the
clutch member 45 is disposed in the downshift position at the right end, and the
rotation from the driver 22 is transmitted to the hub shell 23 after being reduced in speed
via the downshift power transmission path. Specifically, the rotation inputted to the
driver 22 is transmitted to the ring gear 43 via the second one-way clutch 51. At this
point, the clutch pawl 53 of the first one-way clutch 50 is rotated by the clutch
member 45 to the retracted attitude shown by the two-dot chain line in Figure 4, and
the first one-way clutch 50 is in a power cutoff state. Accordingly, the rotation
transmitted to the ring gear 43 is further transmitted to the hub shell 23 via the planet
gear mechanism 24, the gear frame 41, and the third one-way clutch 52. In this case,
the inputted rotation is reduced in speed according to the gear shift ratio determined by
the numbers of teeth of the sun gear 40, the planet gears 42, and the ring gear 43.
[ 4Mfe] Meanwhile, if the winding lever of the shift control component 9 is
operated, the link member 71 of the bell crank 26 swings and pushes in the push rod 48 by one stage,' As a result, since the spring force of the first coil spring 60 is greater than the spring force of the second coil spring 61, the shift key 49 is pushed by the link member 71 via the push rod 48, guided into the second through-groove 21d, and moved to the left in Figure 3 while rotating around the hub axle, and the clutch member 45 is also pushed and moved via the stop ring 63. Once the clutch member 45 is disposed in the direct drive position shown in Figure 9, the clutch pawl 53 of the first one-way clutch 50, which had been put into a retracted attitude by the taper surface 45d, is returned to the erected attitude shown by the solid line in Figure 4 by the spring force of the torsion coil spring 55. In this state, the first one-way clutch 50 is able to transmit only rotation in the forward direction from the ring gear 43 to the

hub she!! 23. Therefore, the rotation from the driver 22 is directly transmitted to the hub shell 23 through the direct drive power transmission path. Specifically, the rotation inputted to the driver 22 is transmitted to the ring gear 43 via the second one-way clutch 51, then is transmitted to the hub shell 23 via the first one-way clutch 50, and the rotation of the driver 22 is transmitted directly to the hub shell 23 via the ring gear 43. At this point, the rotation is transmitted from the ring gear 43 to the gear frame 41 via the planet gear mechanism 24, and the gear frame 41 rotates at reduced speed, but since the rotation of the hub shell 23 is faster than that of the gear frame 41, there is no transmission of the rotation from the gear frame 41 to the hub shell 23 via the third one¬way clutch 52.
fe*G4^] When the winding lever is operated from the direct drive state and the
push rod 48 is pushed in further, the shift key 49 moves further to the left, and the
clutch member 45 also moves correspondingly to the upshift position. When the clutch
member 45 is disposed in the upshift position shown in Figure 10, the serration outer
teeth 45c of the clutch member 45 and the serration inner teeth 41b of the gear
frame 41 mesh with each other. In this movement to the upshift position, when the
serration outer teeth 45c and the serration inner teeth 41b are disposed in the positions
where they mesh, the clutch member 45 moves directly to the upshift position to the
left after the clutch member 45 strikes the gear frame 41. When, however, [these
teeth] are disposed in positions where they do not mesh, the shift key 49 and the clutch
member 45 temporarily halt their movement to the left at the point when the clutch
member 45 strikes the gear frame 41. When this happens, the actuator 66 of the push
rod 48 retracts, the first coil spring 60 is compressed, and the shift key 49 is pressed.
When the clutch member 45 then rotates and the two sets of teeth 45c and 41b reach
their meshing positions, the spring force of the first coil spring 60 moves the clutch
member 45 via the shift key 49, and the two sets of teeth 45c and 41b mesh.
[ 9W**J In this state, the rotation transmitted to the driver 22 is transmitted to the
hub shell 23 via the upshift transmission path. Specifically, it is transmitted from the driver 22, through the clutch member 45, and to the gear frame 41, and the rotation transmitted to the gear frame 41 is transmitted to the hub shell 23 via the planet gear mechanism 24, the ring gear 43, and the first one-way clutch 50. In this case, the inputted rotation is increased in speed and outputted according to the gear shift ratio determined by the numbers of teeth of the sun gear 40, the planet gears 42, and the ring gear 43. There is an attempt at this point to transmit the rotation from the driver 22 toward the ring gear 43 via the second one-way clutch 51, but since the rotation of

the ring gear 43 is faster than that of the driver 22, no rotation is transmitted from the second one-way clutch 51,
H^Mfe] Since rotation is transmitted directly between the driver 22 and the ring
gear 43 during such a shift from the downshift side to the upshift side, it is best to move the clutch member 45, which has no force acting upon it. Accordingly, the spring force of the first coil spring 60 for pushing the clutch member 45 may be reduced, and light shift operation can be achieved.
Upshift-Downshift Assist Actuation
When the release lever of the shift control component 9 is operated at the upshift position shown in Figure 10, the energizing force of the first coil spring 60 is removed, and the second coil spring 61 presses on the shift key 49 and causes the push rod 48 to retract by one stage to the right. The shift key 49 then presses on the clutch member 45 via the third coil spring 62, and attempts to move the clutch member 45 to the direct drive position. When the rider is not pedaling and no drive force is being transmitted, the clutch member 45 separates from the gear frame 41, and the clutch member 45 moves to the direct drive position. If the rider is pedaling, however, since drive force is being transmitted from the clutch member 45 to the gear frame 41, frictional force may cause the serration inner teeth 41b and the serration outer teeth 45b to remain meshed. In a case such as this, the spring force of the second coil spring 61 alone will not move the clutch member 45 !o the right in Figure 10. In a state such as this, when the shift key 49 strikes the flat surface 47a of the cam surface 47 of the clutch member 45 as shown in Figure 5, the shift key 49 is pressed against the walls of the second through-groove 21d over the entire length of the portion inserted in the second through-groove 21d, and is prevented by frictional force from escaping in the axial direction. As a result, when the shift key 49 rides up on the inclined surface 47c, the clutch member 45 moves to the right. When the serration inner teeth 41b and the serration outer teeth 45c are then unmeshed, the clutch member 45 is pressed by the second coil spring 61 via the shift key 49 and moves to the direct drive position. Specifically, contact between the cam surface 47 of the clutch member 45 and the shift key 49 assists shifting by converting the rotational motion of the clutch member 45 into displacement.in the axial direction.
J££*fa| Here, the shift key 49 cannot readily escape to the left in the axial
direction as mentioned above because it is pressed by the second coil spring 61, and the second through-groove 21d is inclined and twisted in a spiral with respect to the axis. Therefore, the shift key 49 will not escape in the axial direction when the transmitted

1
Irive force is less than the energizing force of the second coil spring 61 and the
rictional force between the shift key 49 and the guide surface 21c. However, when a
Irive force greater than these is applied, the shift key 49 may overcome the energizing
brce of the second coil spring 61 and the frictiona! force with the guide surface 21c
nd escape to the left in the axial direction without the clutch member 45 moving. The
.bove-mentioned factional force here can be set by means of the groove inclination
ngle p. If this groove inclination angle [3 is set to high, then it will be difficult for the
hift key 49 to move to the left when the shift key 49 is pushed by the push rod 48. If
iiis is set too low, however, the resistance will be smaller during pushing by the push
od 48, but the frictional force will also decrease. Therefore, this groove inclination
ngle 3 should be between 10 and 50 degrees. It is possible to adjust the drive force at
le limit where the shift key 49 escapes during assist by adjusting this groove
iclination angle p\ the inclination angle a of the inclined surface 47c of the cam
urface 47, and the spring force of the three coil springs 60 to 62.
MNb] Meanwhile, even when a drive force larger than the set drive force is
pplied, and the shift key 49 escapes in the axial direction without the clutch lember 45 moving, once the gear crank 18 reaches the vicinity of top dead center or ottom dead center and the drive force decreases, the clutch member 45 will be pressed y the assist force produced by the shift key 49, and will move to the right. Lccordingly, a shift will not be performed when an extremely large drive force is pplied, such as on a steep hill, which reduces shifting shock and helps prevent damage ) the drive force transmission parts, such as the serration teeth and the one-way lutches.
$G*#^ ' When the clutch member 45 moves, the shift key 49 is separated from
le cam surface 47 by the third coil spring 62. Accordingly, there will be no noise
enerated by contact with the shift key 49 even if the clutch member 45 is rotated. In
le direct drive position shown in Figure 9, rotation is transmitted from the driver 22 to
le hub shell 23 via the direct drive transmission path, as discussed above,
tt*^ When the release lever is operated in a state in which the clutch
iember 45 is disposed in the direct drive position, the push rod 48 retracts further, and Le shift key 49 presses on the clutch member 45. At this point the taper surface 45d of ie clutch member 45 comes into contact with the clutch pawl 53 of the first one-way .utch 50 and attempts to lower the clutch pawl 53 from an erected attitude to a stracted attitude. However, because the clutch pawl 53 is transmitting power from the ng gear 43 to the hub shell 23, it is not readily lowered to a retracted attitude by the lergizing force of the second coil spring 61 alone. Here again, when the shift key 49

strikes the cam surface 47 of the clutch member 45, an assist force is generated just as discussed above, the clutch member 45 is moved in the axial direction, and the clutch pawl 53 can be lowered.
[JMih4 Here, since rotation is transmitted directly to the ring gear 43, without
going through the clutch member 45, there is a reduction in the operating force required during shifting in an upshift operation from the downshift side to the upshift side. Furthermore, since the rotational force of the clutch member 45 is assisted by being converted into displacement in the axial direction in a downshift operation from the upshift side to the downshift side, the rider can make a shift with a light force while still pedaling, even when upshifting.
fr^W^t Also, since the bell crank 26 is mounted to the inside of the hub axle
end, the bell crank 26 does not protrude outward from the hub axle end, which prevents damage to the bell crank 26 and makes it less likely that objects will Tut or snag on the bell crank 26.
Other Practical Examples
(a) The structure of the bell crank 26 is not limited to that in the above embodiment, and many different variations are also possible.
(b) The bell crank 26 is not limited to the mounting position given in the above embodiment, and when it is disposed in the upshift position when the inner cable has not been operated, the bell crank 26 should be mounted to the left in Figure 2.
[ 4HV^ (c) The mechanism for transmitting rotation is not limited to a planet
gear mechanism, and may instead be an outer tooth type of transmission mechanism, a belt, roller, or other type of transmission mechanism, or any of many other variations . Similarly, a variety of structures are possible for the planet gear mechanism. For instance, the planet gear mechanism may comprise two planet gear units set up next to each other on the right and left, and a one-way clutch may be disposed between these planet gear units.
Merits of the Invention
As discussed above, with the internal shifter hub pertaining to the present invention, the movement mechanism is mounted to the inside of the hub axle end, so the movement mechanism does not protrude outward from the hub axle end, which

'1
prevents damage to the movement mechanism and also makes it less likely that objects will hit or snag on the movement mechanism.
Brief Description of the Drawings
Figure 1 is a side view of a bicycle in which an embodiment of the present invention is employed;
Figure 2 is a vertical cross section of the structure of the internal shifter hub thereof;
Figure 3 is an enlarged detail view of the downshift position of this internal shifter hub;
Figure 4 is an oblique detail view of the operation mechanism;
Figure 5 is a schematic of the relation between the shift key and the cam surface;
Figure 6 is a cross section of the lateral portion of the push rod;
Figure 7 is a diagram of the bell crank;
Figure 8 is a cross sectional side view of the bell crank;
Figure 9 is a diagram corresponding to Figure 3 of the direct drive position of the internal shifter hub; and
Figure 10 is a diagram corresponding to Figure 3 of the upshift position of the internal shifter hub.
Key:
2 frame body
7 rear wheel
21 hub axle
22 driver
23 hub shell
24 planet gear mechanism
25 operation mechanism
26 bell crank 32 hub cog

WE CLAIM:
1. An internal hub transmission for a bicycle comprising: a hub axle having
an axle axis for retaining the transmission to a bicycle frame; a driver rotatably supported relative to the hub axle; an output member rotatably supported relative to the hub axle; a planet gear mechanism having: a sun gear disposed around the hub axle, a gear frame rotatably supported relative to the hub axle, a planet gear rotatably supported on the gear frame and meshing with the sun gear, a ring gear rotatably supported relative to the hub axle and meshing with the planet gear; a first one-way clutch disposed in a transmission path between the driver and the output member; a second one-way clutch disposed in a transmission path between the driver and the ring gear; a clutch member supported on the axle for selectively changing the transmission path between the driver and the output member, wherein the clutch member rotates around the axle in response to rotation of the driver and moves axially relative to the hub axle; and a clutch control component that provides movement of the clutch member in the direction of the axle axis and which engages the clutch member for converting rotational motion of the clutch member into motion of the clutch member in the direction of the axle axis.
2. The internal hub transmission according to claim 1 wherein the clutch control
component comprises: a guide surface retained to the hub axle; a shift key which
moves along the guide surface for causing movement of the clutch member in the
direction of the axle axis; and a shift key moving component for moving the shift key.
3. The internal hub transmission according to claim 2 wherein the clutch
member has a cam surface extending in the direction of the axle axis, and the shift key
presses against the cam surface for converting rotational motion of the clutch member
into motion of the clutch member in the direction of the axle axis.

4. The internal hub transmission according to claim 3 wherein the hub axle has a spiral groove, said spiral groove forms the guide surface.
5. The internal hub transmission according to claim 4 wherein the guide surface inclines from approximately 10° to approximately 50° relative to the axle axis.
6. The internal hub transmission according to claim 4 wherein the cam surface is inclined from approximately 20° to approximately 70° relative to the axle axis.
7. The internal hub transmission according to claim 6 wherein the guide surface inclines from approximately 10° to approximately 50° relative to the axle axis.
8. The internal hub transmission according to claim 4 wherein the spiral groove extends through the hub axle.
9. The internal hub transmission according to claim 8 wherein the shift key has a triangular cross-sectional portion disposed within the spiral groove and perpendicular to the axle axis.

10. The internal hub transmission according to claim 9 wherein the triangular cross-sectional portion contacts the guide surface.
11. The internal hub transmission according to claim 2 wherein the clutch member selectively engages the gear frame for transmitting rotational motion of the driver to the gear frame.
12. The internal hub transmission according to claim 11 wherein the shift key moving component causes movement of the shift key toward the gear frame.

13. The internal hub transmission according to claim 12 wherein a first biasing member is provided for biasing the clutch member toward the gear frame; a second biasing member is provided for biasing the shift key toward the clutch member; and a third biasing member is provided for biasing the shift key away from the clutch member.
14. The internal hub transmission according to claim 13 wherein the shift key presses against the clutch member in opposite directions of the axle axis.
15. The internal hub transmission according to claim 14 wherein the shift key moving component comprises: an actuator contacting the shift key; and a control member slidably engaging the actuator; wherein at least one of the first biasing member, the second biasing member and the third biasing member is disposed for biasing the actuator and the control member in opposite directions.
16. The internal hub transmission according to claim 15 wherein the actuator has means for pressing the shift key toward the gear frame.
17. The internal hub transmission according to claim 16 wherein the first biasing member is disposed for biasing the actuator and the control member in opposite directions, wherein the first biasing member has a greater biasing force than the second biasing member, and wherein the second biasing member has a greater biasing force than the third biasing member.
18. The internal hub transmission according to claim 17 wherein the clutch member selectively engages and disengages the first one-way clutch.
19. The internal hub transmission according to claim 18 wherein the first one-way clutch is disposed in a transmission path between the ring gear and the output member.

20. The internal hub transmission according to claim 19 comprises a third one¬way clutch disposed in a transmission path between the gear frame and the output member,
21. The internal hub transmission according to claim 1S wherein the clutch member has a cam surface extending in the direction of the axle axis, and wherein the shift key presses against the cam surface for converting rotational motion of the clutch member into motion of the clutch member in the direction of the axle axis.
22. The internal hub transmission according to claim 21 wherein the
hub axle has a spiral groove, wherein the spiral groove forms the guide surface.
23. The internal hub transmission according to claim 22 wherein the guide surface inclines from approximately 10° to approximately 50° relative to the axle axis.
24. The internal hub transmission according to claim 22 wherein the cam surface is inclined from approximately 20° to approximately 70° relative to the axle axis.
25. The internal hub transmission according to claim 24 wherein the guide surface inclines from approximately 10° to approximately 50° relative to the axle axis.
26. The internal hub transmission according to claim 22 wherein the spiral groove extends through the hub axle.
27. The internal hub transmission according to claim 26 wherein the shift key has a triangular cross-sectional portion disposed within the spiral groove and perpendicular to the axle axis.

28. The internal hub transmission according to claim 27 wherein the triangular cross-sectional portion contacts the guide surface.
29. The internal hub transmission according to claim 15 wherein the actuator presses the shift key away from the gear frame.
30. The internal hub transmission according to claim 29 wherein the second biasing member is disposed for biasing the actuator and the control member in opposite directions, wherein the second biasing member has a greater biasing force than the third biasing member, and wherein the third biasing member has a greater biasing force than the first biasing member.
31. The internal hub transmission according to claim 30 wherein the clutch member selectively engages and disengages the first one-way clutch.
32. The internal hub transmission according to claim 31 wherein the first one-way clutch is disposed in a transmission path between the ring gear and the output member.
33. The internal hub transmission according to claim 32 further comprising a third one-way clutch disposed in a transmission path between the gear frame and the output member.
34. The internal hub transmission according to claim 31 wherein the clutch member has a cam surface extending in the direction of the axle axis, and wherein the shift key presses against the cam surface for converting rotational motion of the clutch member into motion of the clutch member in the direction of the axle axis.
35. The internal hub transmission according to claim 34 wherein the hub axle

has a spiral groove, wherein the spiral groove forms the guide surface.
36. The internal hub transmission according to claim 35 wherein the"guide surface inclines from approximately 10° to approximately 50° relative to the axle axis.
37. The internal hub transmission according to claim 35 wherein the cam surface is inclined from approximately 20° to approximately 70° relative to the axle axis.
38. The internal hub transmission according to claim 37 wherein the guide surface inclines from approximately 10° to approximately 50° relative to the axle axis.
39. The internal hub transmission according to claim 35 wherein the spiral groove extends through the hub axle.
40. The internal hub transmission according to claim 39 wherein the shift key
has a triangular cross-sectional portion disposed within the spiral groove and perpendicular to the axle axis.
41. The internal hub transmission according to claim 40 wherein the triangular cross-sectional portion contacts the guide surface.
42. The internal hub transmission according to claim 13 wherein the second biasing member has a greater biasing force than the third biasing member, and wherein the third biasing member has a greater biasing force than the first biasing member
43. The internal hub transmission according to claim 42 wherein the clutch member is capable of selectively engaging s and disengaging the first one-way clutch.

44. The internal hub transmission according to claim 43 wherein the first one¬way clutch is disposed in a transmission path between the ring gear and the output member.
45. The internal hub transmission according to claim 44 wherein a third one¬way clutch is disposed in a transmission path between the gear frame and the output member.
46. The internal hub transmission according to claim 43 wherein the clutch member has a cam surface extending in the direction of the axle axis, and wherein the shift key presses against the cam surface for converting rotational motion of the clutch member into motion of the clutch member in the direction of the axle axis.
47. The internal hub transmission according to claim 46 wherein the
hub axle has a spiral groove, wherein the spiral groove forms the guide surface.
48. The internal hub transmission according to claim 47 wherein the
guide surface inclines from approximately 10° to approximately 50° relative to the axle axis.
49. The internal hub transmission according to claim 47 wherein the cam surface is inclined from approximately 20° to approximately 70° relative to the axle axis.
50. The internal hub transmission according to claim 49 wherein the guide surface inclines from approximately 10° to approximately 50° relative to the axle axis.
51. The internal hub transmission according to claim 47 wherein the spiral groove extends through the hub axle.

52. The interna! hub transmission according to claim 51 wherein the shift key
has a triangular cross-sectional portion disposed within the spiral groove and
perpendicular to the axle axis.
53. The internal hub transmission according to claim 52 wherein the
triangular cross-sectional portion contacts the guide surface.
54. An internal hub transmission for a bicycle substantially as hereinabove
described and illustrated with reference to the accompanying drawings.